US1510124A

US1510124A - wicks

Info

Publication number: US1510124A
Authority: US
Publication date: 1924-09-30
Anticipated expiration: 1941-09-30

Description

se t; so, 1924. 1,510,124

' J. WICKS MULTIOFFICE TELEPHONE SYSTEM Filed Nov. 15 1919 9 Sheets-Sheet 1 Jul-1n ibks I I Sept. 30., 1924. 1,510,1 4

J. IWICKS MULTIOFFICE TELEPHONE SYSTEM Filed Nov. 15. 1919 9 Sheets-Sheet 2 'lnuenim" JuhnYn/Eks Fifi 7 p Sept. 30. 1924. 1,510,124 J. WICKS MULTIOFFICE TELEPHONE SYSTEM Filed Nov. 15 1919 9 Sheets-$heet y [W Jul-m MHz ks Sept. 30, 1924. 1,510,124

J. WICYKS MULTIOFFICE TELEPHONE SYSTEM Filed Nov. 15, 1919 9 Sheets-Sheet 4 [nusniur Juhn MERE Sept. .30, 1924. 1,510,124

J. WICKS MULTI OFFI CE TELEPHONE SYSTEM Filed Nov. 15 1919 9 Sheets-Sheet 5 [limb-r Jul-m 11/1515.

HIT y:

Spt. 30,1924. 1 1,510,124

J. wlcKs MULTIOFFICE TELEPHONE SYSTEM Filed Nov. 15 1919 9 Sheets-Sheet 6 I'm" Juhn Zn/Taks HIT y:

Sept. 30. 1924. 1,510,124

' J. wlcKs A MuLT16FFIcE TELEPHONE SYSTEM Fil ed Nov. 15, 1919 9 Sheets-Shet 7 [nuanlnr Jmhn Znlzcks Sept. 30, 1924. 1,510,124

J. WICKS MULTIOFFICE TELEPHONE SYSTEM Filed Nov. 15. 1919 9 Sheets-Sheet 8 1m Jul-m HzEks Sept. 30, 1924. 1,510,124

J. WICKS MULTIOFF'ICE TELEPHONE SYSTEM Filed Nov. 15. 1919 9 Sheets-Sheet 9.

'6 7 a ,Start' 11111511151 J 'h W1 i;

Patented Sept. 30, 1924.

1,510,124 PATENT OFFICE.

JOHN WICKS, OF CHICAGO, ILLINO'IS, ASSIGNOR T0 AUTOMATIC ELECTRIC. COMPANY,

' OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

MULTIOFEIOE TELEIHONE 'SYSTEML Application filed November 15, 1919. Serial No. 338,380.

ephone Systems, of which the following is a specification. ,i My invention relates in general to multioffice telephone'systems and isparticularly well adapted for use in such systems as are going thru a period of transition from man ual'operation to automatic operation, there being-some offices or exchanges of the system which have full automatic equipment while the other oflices still have the manual equipment. However, certain features of the invention are of value in ordinary manual inulti-oifice systems not including automatic equipment, while certain other features are applicable to the so called semiautomatic I systems, although it is conceived that the-invention broadlywill find its chief use under the circumstances firststated.

In changing a large manualmulti-ofiice system 'over'to automatic equipment it is considered thebest practice to do so gradually, one office at a time, rather than to attempt to change all ofiices at once. In fact the latter method would in practice be very diliicult if not impossible to accomplish successfully. It follows therefore that after the changeover is started and until it is completed certain of the offices will have auto matic equipment while the others still have the operators, The 'problem then is pre sented of providing suitable trunking facilities between manual and automatic exchanges. I v This invention is not concerned especially withthe trunking from the automatic exchanges to the manual, there being suitable means available already for handling such traffic, but itsobject is toprovide a newv and better arrangement of trunking from the manual oflices'to theautomatic ofiices, and incidentally,'in order topermit a uniform routine of operation on the part ofthe operators, to provide an improved trunking arrangement between the manual oflices themselves. J I, I

o Other objects jconsist in providing improved circuit details and mechanism which with the improved trunking arrangements above mentioned will be fullydescribed heretermed the No. 1 oflice or exchange.

inafter, reference being had to the accom panying drawings.

Referring to the drawings, Fig. 1 is -a schematic diagram showing the trunking arrangement between two manual offices, while Figsy3 and 4 are circuit diagrams showing the apparatus required to establish a complete connection between subscribers in ,dif ferent manual oflices which are interconnected by a system of trunks such as is shown in Fig. l. The left hand portion of Fig. 1 up to the dotted line and Fig, 2 shows a schematic diagram of. the trunking arrangement used for handling calls from a manual oflice to an automatic ofiice. The remaining sheets of drawings, Figs. 5 to, 9,.-inelusive, taken inv connection with Fig. 3, show circuits of the apparatus used in completing a connection from a subscriber in the manual oiiice to a subscriber in an automatic oflice, according to the second trunking arrangement, or at least so much of the circuits is shown as is necessary to enable the invention to be understood. .The general system of trunking from a manual oflice to a second manual officewill first be briefly explained. Referring to Fig. 1, jacks J to J are four of a plurality of outgoing trunk jacks at the A board of a manual ofiice which will hereinafter be These jacks are preferably multipled in a certain number of other positions as'indicated; and are directly connected to primary rotary line switches P tol, respectively. Thesel-ine switches may be of 25 line capacity and as each of the switches shown has access toa different plurality of trunks there will be 100 trunks extending to the second or No. 2 manual'oiiice. Each of these trunks terminatesat the No. 2 office in a secondary rotary'line switch, and four of these switches are indicated by reference characters S to The number of cord circuits at the B- board in the No. 2 exchange for handling calls from the No. 1 exchange should be somewhat in excess of thenumber of trunks, allowing for repairs, etc, and we may assume that 120 cord circuits are provided which are divided into two groupsof cord circuits for each of two positions. Four cord circuits C to C are shown,-which arelocated at thelst position and the other four, C to C are at the 2nd position. These cord circuits are accessible tothe sec ondary switches such as S, S etc., and may bemultiplied in the banks of these switches as desired, care being taken however to give each switch access to cord circuits in both positions. In the present case the switches S, S etc., may be 30 point switches and may be divided into 4 groups having access to 15 cord circuits at each position. Of course the capacity of the switches is immaterial, and they may be of any desired capacity. It has been stated above that the jacks J, J etc., are multipled in other positions. In the case of a large A board as is herein contemplated it will usually be best to divide the board into two or more sections and multiple the first group of outgoing trunk jacks only in the first section which may arbitrarily have 10 or more positions, the term section as here used not referring to the standard 3 position section. An independent multiple will be provided for each of the other sections, one such being represented by the jacks J, J, etc., which are connected to primary switches P, P, etc. These switches have access to the same groups of trunks as do the switches P, P etc. Thus it will be seen that an excessively large outgoing trunk multiple at the A board will never be required.

It will be understood that the foregoing explanation considers only the trunking between the No. 1 ofiice and the No. 2 oflice. There will be a similar system of trunks extending from the No. 1 office to each of the other manual offices, as is the usual practice. Likewise there will be a system of trunks from the No. 1 ofiice to each of the automatic ofiices in the system and the trunking to one of these offices, which will be termed the No. 3 oflice, will now be explained.

The outgoing trunk multiples at the A board of the No. 1 oftice are identical so far as general arrangement and trunking is con cerned, whether they extend to manual oflices or to automatic oflices. In view of this fact, it is not considered necessary to show the outgoing trunk multiple to the N0. 3 office because for purposes of illustration Fig. 2 may be joined to Fig. 1 at the dotted line so that the four trunk lines which extend from the first contacts of primary switches P to P will continue into Fig. 2 and terminate in secondary switches S to S respectively. These latter switches may be of 30 trunk capacity and are divided into four groups, there being shown one switch of each group. There will be therefore a total. of 120 trunks in the layout as shown, and each trunk extends by way of a relay equipment such as M to a first selector switch such as H. It will be seen that there are two B operators positions, each being arranged to handle 60 trunks. Considering the first position, the 60 trunks are divided into threegroups of 20 trunks each and calling devices or operator's senders N, N, and. N are provided which control the establishment of connections over the 3 groups of trunks, respectively. All three senders are in turn controlled by the operator thru the medium of a set of keys indicated by references character K. The arrangement at the second position is the same. In multiplying the trunks in the banks of the switches S S, etc., the arrangement should be such that there are a certain number of trunks, 5 in this case, extending from the banks of each of the four groups of switches to each of the 6 operatorssenders; or in other words, the 20 trunks controlled by each sender should be divided into as many groups as there are groups of secondary switches and each group of trunks should then be multipled in the banks of a different group of switches.

The foregoing will be sufficient it is believed to make clear the general layout of the system. The method of operation and the circuits will be described fully in the de tailed specification which is to follow. In order to reduce the amount of descriptive matter in the specification, the apparatus used, such as the automatic substations, the primary and secondary line switches, the selector switches and other switches comprising the automatic exchange, and the operators senders and key equipment, will not be described in detail, but instead reference is made to the following patents: British patent to Dicker #29554 of 1910, U. S.

patent to Land #1,14t6,177, U. S. patent to Lamb $51,193,160, U. S. patent to Keith Erickson and Erickson #815,321, U. S. patent to Keith Erickson and Erickson #815,- 176, U. S. patent to Blessing 51,209,253, 'U. S. patent to Powell #1,308,553.

Having given a general description of the trunking system as a whole, I will now describe the operation thereof more in detail, it being assumed first, referring to Figs. 3 and et, that the subscriber at substation A whose line is connected to the No. 1 office desires to obtain connection with the subscriber at substation A whose line is connected to the No. 2 ofiice. Vhen the subscriber at substation A removes his receiver from the hook a circuit is completed which extends from ground thru the cut off relay 2, over the line and thru substation A, and returning on the other side of the line thru the line relay 3 to battery. The line relay 3 is energized upon the closure of the above circuit and completes a circuit for the line lamp L; but relay 3 being of high resist ance, the cut off relay 2 is prevented from energizing at this time. \Vhen the operator observes the lighted condition of the lamp L she will respond by inserting the answering plug of an idle cord circuit, for example the cord circuit C, in the jack J, at the same time throwing her listening key K. Upon the insertion of the plugin. the jack a circuit is completed over the tip of the plug which connects the cut off relay 2 and the relay 4.01 the cord circuit in series. Both relays are energized, relay 4 closing a pair of contacts in the circuit of the supervisory lamp L, and the cut cit relay switching the ring side of the line from connection with the line relay 3 into connection withthe sleeve of jack J, thereby placing a potential upon the sleev'eoif jack J and its multiples (not shown) whereby the line of substation A is made busy at other positions. At the same time that relay 4 is energized as described relay 5 is also energized over a circuit which extends from ground thru out off relay 2, thrusubstat ion A, and back over the ring side of the line thru relay ,5 to battery. Relay 5 opens a pair of contacts in the circuit of the supervisory lamp L.

,Vhen the subscriber at substation A hears the operator on the line, he will re peat the number of the subscriber with avhoni he wishes to be co-i'inected, as is the well known practice. Upon learning that the desired subscriber IS in the No. 2 ofiice,

" the operator will test the outgoing trunk locate an idle jack.

multipleot the No. 2 office with the tip of her plug in the usual manner in order to Assuming that the jack J is found to be idle the operator will insert the calling plug, whereupon. a circuit is completed for the relay 6 as follows:

" Ground at G, restingcontact of armature 18 andthe said armature, ring springof jack J", ring of plug, and the winding of relay 6 to: battery. Upon energizing, relay 6 opens a pair of contactsin the circuit of the lamp L and also completes an initial energizing circuit for relay 7 which extends as follows; Ground at G windingof relay 11 tip spring of jack J, tip of plug, contacts of relay .6, and the winding of relay 7 to battery. Upon energizing relay 7 closes its own circuit independent of relay,

6 and also prepares a circuit for the'supervisory lamp L w The energization. of relay 1.1, which is the line relay of the primary line switch P", over the circuit described above, causes the initiation of the trunk selecting movement of this switch whereby an idle trunk line extended to the No. 2'o1fice is selected.

Upon attracting its armature 14, relay 11 I test contact with which the test wiper 22 is 21, 22, and 23 step by step in search of an idle trunk extending to the No. 2exchange.

This is the usual operation of a rotary switch otthis type in the case where its operation is initiated when its wipers are standing upon the contacts of a trunk line which is busy. However, in the present case we may assume that when the operation of the line switch P is initiated itswipers are standing upon the contacts which are terminals of the trunk conductors and 27 as shown in the drawing, and we may assume furthermorethat this trunk line is idle at the time. Under these circumstances, when the circuit of the switchingrelay 12 is closed thru the stepping magnet 13 the said relay 12 will not be short circuited and the stepping magnet will not operate owing to the high resistance of relay 12; The relay 12 is energized with the following re sults; At its armature 18 ground G is disconnected from the ring side of the line circuit thereby causing relay 6 in the cord circuit to deenergize and close the circuit.

of the calling supervisory lamp L 1 At armature 17 ground G? is connected to the test wiper 22 thereby completing a circuit over the conductor 26 to the'relay 28,'which is one of a series of chain relays'which are provided, one for each trunk, for the purpose of connecting battery to the common conductor 29 whenever all the outgoing trunks in the group become busy, The

sleeves of the jack are all normally con- 'nected to this common conductor 29 by way 'tacts of armatures 33 and 34-. of relay to the winding of the line relay 31 of the secondary line switch S.

It will be seen that the line relay 31 is thereby bridged across the line and will be energized by current flow from ground at G thru the line relay 11 of the primary line switch 1P, over the upper line conductor, thru the said line relay 31, over the lower line conductor and thru the winding of relay"6 of the cord circuit C to battery.

Relay 31 is of high resistance and does not permit enoljlgh current to flow to cause the operation of relay 6, but energizes immediately itself and closes a circuit for the relay 32. Upon the operation of relay 32 circuits are closed which correspond to similar circuits whose operation has been described in connection with the primary line switch P,

whereby the secondary switch S is caused to select and establish connection with an idle cord circuit. These operations having already been described will not be considered again in detail, but it will be suf iicient to say, assuming that the cord circuit C is idle, that the switching relay 30 is energized, whereby the line conductors are extended by way of armatures 33 and 34 and their working contacts, wipers 4L0 and 42, the bank contacts with which these wipers are in engagement, and the upper and lower windings of the repeating coil R to the windings of the relay 60. Relay 60, or at least its left hand winding, is of high resistance and this relay is now energized over a. circuit similar to that by which the line relay 31 of the secondary switch S was energized, relay 6 at the cord circuit C" re maining inoperative as before. Upon energizing, relay 6O completes a circuit which extends as follows: Ground G working con tact of armature 82 and the said armature, and the winding of relay 43 to battery. Upon energizing in its turn, relay 43 completes a holding circuit for the switching relay 30 of secondary switch S which may be traced over the following path: Ground at G working contact of armature 49 and the said armature, resting contact of armature 83 and the said armature, test contact upon which the test wiper ll is now resting and the said test wiper, armature 35 and its working cont-act, winding of the switching relay 30 and the winding of the stepping magnet 36 to battery.

It is understood that this holding circuit is established before the slow acting relay 32 has had time to deenergize. A branch of the holding circuit just traced extends by way of the resting contact of armature 52 and the said armature to the common conductor 59, thereby grounding this conductor. Conductor 59 is multipled to contact springs corresponding to armature 52 in all the other cord circuits at the position, and when grounded therefore has the function of rendering all the cord circuits busy.

As a further result of the energization of relay 43 ground G is connected by means of armature 50 to the windings of relays l5 and 64-, both of which relays are energized. Relay d5 at its arn'iatures 57 and 58 connects the operators head set across the trunk circuit whereby she is put in communication with the operator at the No. 1 exchange. Relay 64 at its armature 7O closes a circuit for the lamp L" which extends as follows: Ground at. G interrupter I, normally closed contacts controlled by armature 73 of relay 63, armature 74- and its resting contact, working contact of armature and the said armature, and thelamp L to battery.

Connection having been established between the two operators, the A operator will now repeat the desired number to the B operator who, being advised which of her cord circuits is to be used by the flashing of the lamp L will test the desired line and upon finding it idle will insert the plug of cord circuit C in multiple jack J Upon the insertion of the plug a. circuit is completed for the relay 62 as follows: Ground at G winding of relay 62, resting contact of armature 7 8 and the said armature, resting contact of armature 79 and the said armature, ring of plum ring spring of jack J normally closed contacts of the cut off relay 2, and the winding of the line relay 3 to battery. Upon energizing, relay -62 closes the following circuit: Ground at G, working contact of aimature 75 and the said arm-a.- ture, winding of relay 67, and the resistance r to battery. Relay 67 is energized and at its armature 76 completes an energizing circuit for relay 66 which relay at its armature 78 opens the circuit of relay 62. Upon deenergizing, relay 62 breaks the original energizing circuit of relay 67, but this relay is not deenergized, remaining locked up over the following path: Ground at G, winding of the cut off relay, tip spring of jack J tip of plug, armature 80 and its working contact, the winding of relay 67, and the resistance r to battery. ,As a further result of the energization of relay 66 the upper and lower line conductors are closed at the working contacts of armatures 77 and 78, and at armature 7-1 the circuit of the lamp L is broken. ln addition, at the working contact of armature 74 a circuit is established for relay 63 as follows: Ground at G interrupter I (the first time this interrupter closes the circuit), normally closed contacts controlled by armature 73 of relay 63, armature 74 and its working contact, armature 69 and its working contact, and the winding of relay 63 to battery. Upon energizing, relay 63 locks itself independent of relay 64 at its armature 72, and by means of armiature 73 substitutes direct ground for the interrupted ground G A branch of the circuit by which relay 63 was energized may be traced from the junction point 84 by way of armature 56 and its working contact, normally closed contacts controlled by armature 5i, and the winding of relay 44 to battery. Upon energizing relay 4% completes a locking circuit for itself at its armature 51; breaks the circuit of relay 45 at its armature 53, whereby the operators head set is disconnected from the trunk; and at armature 52 removes ground G from the com- I projected out over the called line in the usual 1 Responsive to the hanging up of the re manner to signal the called subscriber. Relay '68 is included in this circuit and is so adjusted that it does not respond to the ringing current as long as the receiver at the called station is on the hook. hen the called subscriber answers, however, relay 68 isoperated, either byringing current from the generator Gen or by direct current from the battery associated therewith, and shortcircuits the winding of the ringing relay 67. Relay 67 is accordingly deenergized and in addition to breaking its ownloc-king circuit at armature this relay opens the original energizingcircuit of relay 66, which is hereafter maintained energized over the tip side of the line to ground G thru the winding of the cut off relay 2, As a further result of its deenergization, relay67 disconnects the ringing current generator and closes the ring side of the line at armature 79. The

rec-eiverbeing off the hook atthe called station a circuitis now established which extends fromground G thru the winding of erated to extinguish the supervisory lamp L The A operator, who has already restoredher keyK, is thus notified that the call has been answered and need pay no further attention to it until one or both of the lamps L and L are again lighted to in-f dicate that the conversation is finished.

The talking circuit between the two connected sub-stations is shown in heavy lines,

and being furthermore of well known character, willnotnee'dto be described in .de-

tail. lVhen the conversation' is over with both subscribers willreplace their receivers.

ceiver at substation A the circuit ofrelay 5 is broken, resulting in the lighting of the supervisory lamp L. l V'hen the receiver is replaced at substationiA relay 61 is deenergized and the high resistance winding of relay 60 is again included in the circuit of relay 6 at the cord circuit C, thereby causing this relay to de'energize and close the circuit of supervisory lamp L The lighting of the supervisory lamps indicates to the operator that the subscribers are tru talking and she will acordingly pull down the connection. \Vhen the calling plug is removed from jack J the circuit of relay 11 of the primary line switch P is broken, whereupon this relay and also the switching relay 12 are dccnergized, thereby restoring the'switch to normal condition ready for another call. As a further result of the removal of the plug from jack J the circuit of relay 60 of cord circuit C is broken and this relay therefore deenergizes to break the circuit of relay 4?). Upon deenergizing, relay 13 breaks the holding circuit of theswitching relay 30 of the secondary line switch S at its armature 19, whereupon relay 3O deenergizes and the secondary line switch is restored to normal 1 its working contact, armature 56 and its rest-V ing contact, armature 4C7 and its resting contaot, and the winding of relay -16 to battery. Relay 4:6 is operated and again grounds the test contact upon which test wiper 41 is resting, and multiples of this test contact (not shown), whereby the cord circuit C is again made busy to incoming calls, the brief interval during .which ground is removed- I from the test contact being just sufiicient to provide for the restoration of the secondary switch S. As a further result of the deenergization of relay 13, ground G is disconnected from the relay 6& and this relay therefore deenergizes to close a circuit for the lamp L which extends as follows: Ground at G, armature 73 and its working contact, armature 74c and its working contact, resting contact of armature 'TOxand the said armature, and the lamp L tobattery. The lighting of the lamp L gives the B operator a disconnect signal, upon perceiving which she will remove the plug from jack J As a result of the removal of'the plug, relay '66 is deenergized, breaking at its armature 74 the circuit of the lamp L and also the circuit or relay46. Relay 46 therefore deenergizes also removing ground from the multiple test contacts associated with cord circuit C, whereupon the cord circuit Wlll be agaln n normal condition and ready for another call.

Having described the operation of the circuits involved in the establishment'of a connection between a subscribers-line connected to the No. 1 oflice and a second subscribers line connected. to the No. 2 ofiice, both of which ofiices have manual equipment, I will now describe the operation of the circuits involved in establishing a connection between a subscribers line con-- nected to the No. 1 oiiice' and a subscribers .the desired line is connected to the numher .3 or automatic office. In this case, then, the A operator in order to extend the connection will test the out going trunk multiple associated with the No. 3 office, and upon finding an idle jack, assumed in this case to be jack J will insert the calling plug of the cord circuit C. When the operator plugs into the jack the primary switch P will be operated to extend the connection to an idle trunk line which will be assumed to be the trunk line extending to the secondary switch S Fig. 5; and immediately thereafter the secondary switch S will operate to further extend the con nection to an idle relay equipment. Assuming that the relay equipment M, Fig. 5, is found to be idle and that connection is established therewith, the relay 128 will be energized over the line circuit. Relay 128 will be recognized as a relay normally having a high resistance, corresponding to the relay 60 of cord circuit C. It follows that relay 6 of cord circuit C will remain inoperative and the supervisiory lamp L -will continue to glow. Upon energizing, relay 128 closes the circuit of slow acting relay 129 which relay, upon attracting its armature 1 12, connects the righthand windings of the repeating coil *1 across the trunk conductors 161 and 162 The trunk line comprising conductors 161 and 163 extends to a first selector switch (not shown) and it follows that upon the closure of the line circuit by the operation of relay 129 the line and release relays of the first selector will be energized in the usual manner thereby preparing the selector for operation responsive to interruptions subsequently produced'in the line circuit in accordance with a digit in the called numher. At its armature 1521 relay 129 also closes a contact in the circuit of relay 111 for a purpose to be described hereinafter; and at its armature 140 connects ground G to conductor 162. As a result of this latter operation the visual signal V is actuated and also an energizing circuit is completed for the slow acting. relay 130.

Relay 130 upon energizing completes a holding circuit for the secondary switch S as follows: Ground at G, working contact of 145 and the said armature, test contact with which test wiper 121 is in engagement and the said test wiper, armature 109 and its working contact, winding of relay 106, and the winding of the stepping magnet to battery. This circuit is established before the slow acting relay 108 has had time to deenergize, and in addition to its function of maintaining relay 106 in operated position, it also provides ground to multiple test contacts associated with the relay equipment M in the banks of other secondary switches for the purpose of rendering the relay equipment M busy to other calls. It will be observed that ground G also extends by way of the working contact of 1 5 and the said'armature, armature 148 and its resting contact, and conductor 171 to conductor 171, Fig. 7. Conductor 171 is a common conductor and has connected to it all the conductors similar to conductor 171 which are associated with the other relay equipments of the group which is controlled by the operators sender N. It will be seen therefore that as soon as the relay equip ment M is seized the common conductor 171 will be grounded, resulting in the grounding of all conductors such as conductor 171 which extend to other idle relay equipments in the group; and that since in all idle relay equipments the relays such as relay 130 are deenergized, the effect of grounding conductors such as conductor 171 will be to'placc a busy potential upon the test contacts associated with all the other idle relay equipments of the group. But this is not all. There is a common conductor such as the common conductor 171 sociated with each operators sender, the common conductor associated with the second operators sender being indicated by reference character 271, Fig. 8. All three of these common conductors, assuming that. the operator at this position has thrcecallingdevices, or senders, are connection by way of normally closed relay contacts to another common conductor 201, there being one such latter conductor to each operators position. It follows therefore that when the relay equipment M is seized, not only will all the other relay equipments of the group be made busy, but all the idle relay equipment of the groups associated with the other two operators senders N and bl will be made busy also.

Returning now to the relay 130, as a further result of its energization a circuit is completed for relay 132 which extends as follows: Ground at G, armature 2141 and its resting contact, normally closed contact springs controlled by armature 225, conductor 16 1, armature 1&4 and its working contact, armature 1 17 and its resting contact, and the winding of relay 132 to battery. Upon energizing relay 132 connects the operators head set across the trunk circuit by means of its armatures 150 and 152; and at armature 151 closes a circuit for relay 202, Fig. 7, which may be readily traced over conductor 169. Relay 202 accordingly energizes and at its armature 228 disconnects ground from conductor 2 11 for a purpose which will be explained later, and also at its armature 226 connects ground .to

then depresses the key marked of relay 111 and associated circuits will be explained later on. A, branchof the circult of relay 202 may be traced from junc tion point 242, Fig. 7, thru the windings of

relays

243 and 2 44 in series to battery. These two relays are therefore energized and connect the conductors coming from the operators number setting or register keys shown in Fig, 9 to the operators sender N. When. relay 132 was energized it closed,-in addition to the circuits just described, a circuit which extends from ground G by way of'armature153 and its working contact and the windings of relays 133 and 134 in series to battery. Upon energizing relay 133 establishes a locking circuit for itself and relay 134 which. may be traced as follows: Ground at G, Fig. 7, normally closed contacts controlled by armature 217, armature 211 and its resting contact, normally closed contacts controlled by armature 224, common conductor165 conductor 165,-ar1;pature 154 and its working contact, and the windings of relays 133 and 134 in, series to battery. At its armature 157 relay 133 connects ground to conductor 171 in order to maintain this conductor grounded after the energization of relay 131 which occurs at a further-stage of the operation; and at its armatures 155 and 156 prepares circuits which need not be considered now as they remain open for the time being at other points. Relay 134, upon energizing, disconnects the trunk conductors 161 and 163 from the right hand windings of the repeatingcoil R and connects them instead to

conductors

166 and 167, respectively, which are connected to

common conductors

166 and 167, respectively,'which terminate in the normally closed interrupter or impulse transmitting springs 245 and 246 of the operators sender N;

The foregoing operations have all occurred automatically responsive to the seizure of the relay equipment M by the secondary switch S 2 The B operator having control of the sender 1 .will now be in communication with the A. operator, her

head sethavingbeen connected by the en-' er'gization of relay 132, as previously stated. The A operator knows when the connection to the B operator has been completed by the cessation of the induced tone on the line (produced by signalling equipment Q whilerelay 107 is energized) and will now repeat the desired number. Upon learning the number the B operator de presses in rapid succession the corresponding digit keys of her .key set, Fig. 9, and start. The B operator ordinarily pays no further attention to the call after performing these operations.

In response to the actuation of the digit keys certain ones of a plurality of levers (not shown) arranged radially, on the wheel 249; are set by means of an arm (also not shown) operated by the magnet 252 and controlled by the solenoids 251. In. this way the required number is registered on the wheel 249. Then the first digit key is depressed (and each time a key is depressed thereafter during the setting up of the number) a circuit is closedas follows: Ground at G, winding of relay 206, conductor 254, conductor 255, contacts of any depressed key, conductor individual to the depressed key, and the corresponding solenoid of the sender N. to battery. This will make it clear how. the solenoids and magnet 252 are energized at proper times, the latter magnet being controlled by the relay206 which is energized in series with one of the solenoids every time a digit key is depressed. Relay 206, at its first energization, closes a circuit for relay 207, which upon. energizing, closes a locking circuit for itself at its'armature 218. A circuit may now be traced from ground G by way of normally closed contacts controlled by armature215,

working contact of armature 218 and the said armature, conductor 2'56, andlamp L to battery. Lamp L is lighted when the first keyis depressed and indicates that the sender-is in set or partially set position but is not operating to transmit impulses.

Upon the operation of the starting key a circuit is closed for the relay 209 as follows: b'rround at G, normally closed contacts controlled by armature 215, working contact of armature 218 and the saidarmature, conductor 257, conductor 258, contacts of starting key, conductor 259, condu'ctor260, and

' the winding of relay 209 to battery. Upon attracting its armature 214, relay 209' opens the circuit of relay 132 which relay deenergizes with important results. By retraction of armatures150 and 152 the B operators head set is disconnected. By the retraction of armature 151 the circuit of

relays

202, 243, and 244 is broken, and these relays are deenergized, the latter two disconnecting the register keys from the sender N, and by the retraction of armature 153 a circuit for re lay 203 is closed as followsz'Ground at G, armature 153 and its resting contact, working contact of armature 155 and said armature, conductor 170, common conductor 170, and the winding of relay 203 to battery. Upon energizing, relay 203 connects ground at its armature 227 to conductor 168 which it maintains grounded after relay 202 has deenergized, and at its armature 229 disconnects the common conductor 171 from the common conductor 201. By the latter operation the relay equipments of the groups controlled bycalling devices N and N are placed in idlecondition and are ready to receive calls. This is proper, for although the sender N has not yet performed its function (note that the relay equipments associated with N are held busy for the present) still the operator has done her part, her head set and register keys have been disconnected, and she may well busy herself by setting up another call on one of her other senders. As a final result of its deenergization, relay 132 closes the circuit of relay 131, ground G being extended by way of armature 153 and its resting contact, working contact of armature 156 and the said armature, and the winding of relay 131 to battery. Upon energizing, relay 1231 establishes a locking circuit for itself at armature 1 18 and at armature 147 opens a contact in the circuit of relay 132 to prevent this relay from energizing again after the sender N is restored to normal.

Returning to relay 209, an additional function of its energization is the completion at armature 212 of a circuit for the starting relay 240 of the sender N. Upon energizing the starting relay 24:0 closes the contact springs 272 and 273 which are locked mechanically in closed position. A circuit is thereby completed for relay 208 which upon energizing, closes a locking circuit for relay 209 at its armature 215; breaks the circuit of relay 207 and of lamp L at the contacts controlled by the same armature; opens the circuit of starting relay 240 at armature 216; and finally by attracting armature 217, inserts the winding of the slow acting relay 210 in the previously described locking circuit of relays 133 and 13a of the relay equipment M. Relay 210 is accordingly energized. A branch of the circuit of relay 208 extends over conductor 27 1 to lamp L which is now lighted. A further result of the closure of springs 272 and 273 is the completion of the operating circuit of the motor 250 which now begins to rotate the wheel 249 and the impulse cam 275, the gearing for driving the latter not being shown. The gears are so proportioned that the cam 275 separates the impulse springs 245 and 246 once for each lever (not shown) on the wheel 249 which passes the springs 276 and 277. As soon as the first displaced lever arrives at the latter springs they are closed momentarily thereby completing a circuit for slow acting relay 247. Relay 2 17 closes in turn a circuit for slow acting magnet 248 which operates to bring a pawl into engagement with the impulse cam, thereby stopping the operation of the motor for an interval. As soon as relay 247 and magnet 2 18 retract their armatures the motor again starts to revolve and another series of impulses is transmitted by the cam 275, the number of impulses being determined as before by the displaced lever on the wheel 2&9. It will be clear, therefore, that the impulse sender N will operate to transmit in this manner as many series of impulses over the circuit including trunk conductors 161 and 163 as there were digit keys depressed, the number of impulses in each series being determined by the relative position of the displaced levers, which in turn depends upon which digit keys were depressed.

lVhile the automatic switches which re spoud to the several series of impulses to establish the connection are not shown, they have been described in the patents referred to, and anyway they are well understood by those familiar with the art. It will suffice to say in this connection that a plurality of serially related selector switches and a connector switch are successively operated by the successive series of impulses until the final switch which is the connector coinpletes the connection to the desired line, whereupon suitable ringing mechanism is rendered operative to signal the called subscribe-r.

After the transmission of the last series of impulses, the motor 250 continues to run until the wheel 21-9 has made a complete rotation and returned to its starting point. Upon the return of wheel 21%) to normal the springs 272 and 273 are unlocked and allowed to separate, thereby stopping the mo tor 250, deenergizing relay 208, and extinguishing the lamp L. Upon deenergizing, relay 208 breaks the locking circuit of relay 209 at armature 215, and at armature 217 disconnects ground G from the locking circuit of relays 133 and 131. ielay 210 which is included in this locking circuit is slow acting and hence does not retract its armature 211 until relays 233 and 2341 have had time to deenergize or at least until relay 233 has opened the circuit at another point by retracting its armature 15st. Belay 183, by retracting its armature 157, also removes ground from conductor 171 and, therefore from common conductor 171, with the result that the busy condition is removed from other relay equipments in the group associated with sender N. Furthermore, at armature 155 the circuit of relay 203 is broken, which relay now deenergizes to again connect common conductor 171 with common conductor 201, such being the normal condition.

Relay 13 1, which was deenergized simultaneously with relay 133, has now reconnected the trunk conductors 161 and 163 with the right hand windings of the repeating coil R", these windings being conductively connected by way of the upper winding of the electro polarized relay 126, Now when the called subscriber answers his telephone the direction of current flow in the trunk conductors 161 and 163 is reversed accordingly to the well known practice by a so called reversing relay in the its upper armature 135, and at armature 136 short-circuits the lower and high resistance winding of relay 128. As a result of this latter operation suificient current is permitted to fiow over the inter-oflice trunk comingfrom the'No. 1 oiiice to energize relay 6 of cord circuit C, whereuponthis relay is operated to extinguish the supervisory lamp L this notifying the A operator that the call has been answered.

The desired connection has now been es- So much of the talking circuit as is shown is in heavy lines, and being of the usual charactergtheentire circuit will be understood without difi'iculty;

When the subscribers have finished talking they. will replace their receivers as is customary. Upon the replacement of the receiver at substation Athe supervisory lamp L is lighted as previously explained. When i the receiver is replaced at the called stationwhose lmetermmates 1n the N0. 3 or automatic oiiice the direction of current fiow in trunk conductorsltiland 163 will the circuit of supervisory lamp L By the disconnect signals thus exhibited the A operator is notified that the conversationis over with. and she will accordingly pull down the connection. By the removel of the plug from jack J the primary switch P is restored to normal,- and in addition the energizing circuit of relay 128 is broken.

Relay 128,upon deenergizing, breaksthe circuit of relay 129, whose deenergization is followed by the deenergization of relays 130, 131, and 127 and by the extinguishing of lamp and restoration of the signal V. Relay 130 breaks the holding cir cuit of relay 106 of the secondary switch C which also restores; and relay 129 opens the bridge across trunk conductors 161 and 163 thereb causing the release of the auto- 7 Q matic switches,,whereupon all the apparabus in use wlll have been restored to normal. An explanationwill' now be made of certain other features whichwere not covered before because it was not thought advisable to digress from the description of the routine operations. In Fig. 5 are shown three relays 111, 112, and 113,.which are common to the three groups or trunks associated with tablished and conversation may proceed.

senders N, N and N respectively; and a fourth relay 114, which is common to all the groups of relay equipments at all the positions which are accessible to the secondary switches. Relay 111 may be energized in two ways; either by the closing of a circuit which includes armature 1 11 of relay 129 of the first relay equipment M in the group, the armature lat-1 which is similiarly located in the second relay equipment of the group, and corresponding armatures in all the other relay equipments of the group; or by grounding conductor 168-at

relay

202 or 203. It will be seen then that relay 111 will be energized when all the trunks or relay equipments 111' the group controlled by sender N are busy, and that it will also be energized whenever the sender itself is busy, whether the relay equipments are all busy or not. Relay 112, associated with the group of relay equipments controlled by sender N is energized in a similiar manner, a little more of the circuit being shown becauserelay equipment M is the second in the group rather than the first. Relay 113 (circuits not shown) is energized responsive to busy conditions in the third group in the same manner. There is a similar relay associated with each of the other groups of relay; equipments to which the secondary switches haveaccess, and in the present embodiment of the invention comprising six operators senders (see Fig. 2) there will be three more relays arranged like the ones shown, the circuit through these omitted relays being indicated by the dotted conductor. It will be seen now that when none of the groups of relay equipments are in; condition to receive a call, each group being busy either by reason of the fact that all the relay equipments themselves are busy or because the as sociated sender is in use, then all the relays 111, 112, etc.,will be energized and a circuit will be established for relay 11 1. Relay 11 1,

upon energizing, disconnects ground from the common conductor 109. If we assume now that a secondary switch, the switch S for example, is seized-in the process of extending a connection from the No. 1 ofiice,

when relay 107 is energized over the trunk conductors it will be unable to close the en ergizing circuit of relay 108, the secondary switch being thereby prevented from rotating in search of an idle trunk. This is done because rotation would be useless, there being in fact no trunks idle at th s tune.

i/Vhile the call is being held up in this 3 will rarely occur that the condition will endure for long; and as soon as some group of relay equipn'ients at the No. 3 exchange becomes accessible ground will be restored to conductor 109 and the switch S will operate as usual.

It has been described how the test contacts of the relay equipments in each position are normally tied together by means of the common conductors 171 etc., and the common conductor 201. This arrangement is designed to and ordinarily does render the entire position busy while the operator is engaged in'setting up a call and any sender busy while it is transmitting impulses thereafter, tho the position may then be accessible via trunks associated with other senders.

Nevertheless, it-does happen at comparatively rare intervals that two calls will come in at the same time at the same position, generally being due to two secondary switches being seized at exactly the same instant, or it maybe due to detective busy test circuits. Although as stated this trouble occurs so seldom that it could perhaps be neglected, yet under certain conditions it may be considered worth while to prevent its ill effects and I have devised means-for doing so. Suppose that calls come in to the relay equipments M and M simultaneously. Certain relays pull upin both relay equipmentsuntil finally relays 132 and are energized, followed by the energization of

relays

202 and 302. llelay 202 disconnects ground from conductor 2&1 and hence from conductor 364 which is included in: the energizing circuit of relay 332. It follows that although relays 132 and 382 both operate at once or rather start to operate, the latter relay will immediately fall bacl; so that only one call will be extended to the operator which is the call received at relay equipment ill, the other call being heldup temporarily while the operator is setting the sender N. As soon as sender l is'started transmitting impulses relay 202 oe aergizes thereby permitting relay to operate and extend the delayed call to the operator; meanwhile and until this occurs the A op erator is given a busy signal from the busy ignalling machine Q3 It will be seen that :he normally grounded conductor 24:1. is coped through contacts of relays 202 and 30:, associated with senders N and N respectively, so that the sender ll will have l'erence over the othersenders whenever ...unultaneous calls are received at the position, and sender N will have preference over sender N under similar circumstances. This takes care of calls received simultaneously at relay equipments associated with diilerent senders. But suppose two callsare received simultaneously at relay equipments controlled by the same sender. To take care of this situation each of the conductors such as conductor is looped through normally closed contacts or" the several relays, such as relay 33a, of the several relay equipments or the group. Fig. 6 shows this very clearly, conductor 86% being looped through normally closed contacts of a relay in the 1st relay equipment which corresponds to relay 83d, thence through normally closed con tacts oi relay relay equipment M thence through normally closed contacts of a relay in the third relay equipment which corresponds to relay 83d, and thence through normally closed contacts (notshown) of similar rela s in all the other relay equipments in the'group, there being a branch ta en off at each relay equipment for the purpose or operating the relays such as relays 332. Thus it will beseen that in the case of calls receivedsimultaneously at relayequipments of the same group, the call received at the relay equipment which is closest to the grounded end of conductor 364: (or similar conductor) will have the preference.

Another feature relates-to the provision of means whereby an operator can restore a sender to normal and reset itin case she .mahes a mistake in registering a number.

Suppose the operator is setting up a number on sender It and accidentally depresses a wrong digitlzey. To go ahead under these circumstances and operate the starting hey would result in giving the calling party the wrong number. Instead therefore she will actuate momentarily the release .rey (Fig. 0) thereby closing circuits for

relays

205 and 209. Upon energizing, relay 205 locks itself to ground G and also closes a circuit for relay 20% which relay grounds conductors 16 i and 165 in order to maintain the relay equipment, M- for example, in the status-quo, so to speak, while the sender is running down or returning to normal. This operation is initiated by the energization oi relay 209, as has previously been described, and the automatic switches are prevented from operating by the opening of the impulse transmitting circuit at armature 223 or" relay 205. Vhen thesender has returned to normal relay 205 will be unlocked (this will e clear it the function oi slow acting relay 210 is recalled) and relay 204; will decnergisie an instant later, restoring the circuits over

conductors

164 and 165 to their former condition. The operator is able to tell when the sensor has completely restored by the extinguishing of lamp T 6 and M she will then reset the sender correctly.

What I claim as my invention is:

1. In a telephone system, two manual ollices an automatic o'hice, inter-oiiice trunk lines connecting said offices, A operators at each manual ol'lice for receiving and extending inter-ofiice calls to the proper ofice, B opera- 2. In a telephone system, two ofiicesor exchanges provided wi'th'manual connecting apparatus, for connecting subscribers lines, third ofiice provided with automatic switches for connecting subscribers lines,

intero1'fice trunk lines connecting said of fices,A operatorsat each manual office for receiving and extending inter-office calls to the proper oiiice, B operators at all of said offices for completing int-er ofiice calls, such calls being completed at the said third oflice by means of automatic switches, other automatic switches at the manual ofices, and suitable connectingapparatus and circuits therefor associated with said inter-office trunk lines whereby the A operators in ex tending inter-ofiice calls control said last mentioned switches to select trunk lines to the proper 'oflices and perform the same routine operations whether calls are being extended to the other manual office or to the saidautomatic ofiice.

8. In a-telephone system, an Aboard divided into sections, each comp-rising a I plurality" of positions, a separate outgoing trunk multiple for each section, a separate group of trunking switches'for each mul 'tiple, and a plurality of inter-oflice trunk lines accessible to all of said switches in common. V

4. ln a telephone system, an A board divided into sections, each comprising a plurality of positions, groups of automatic trunking switches, a separate outgoing trunk multiple extending from each sectionand terminating in a plurality ofsaid groups of switches, groups of inter-oflice trunk lines accessible, respectively, to the said group of switches in which one of said multiples terminates, and multiple connections-whereby the groups of switches forming terminals ofsaidother multiples are given access to said groups of trunk lines also.

p 5. In a telephone system, two switch board sections each comprising a plurality of A operators positions, a group of trunklines multipled throughout the first section and divided into sub-groups, each sub-group haying an associated group of primary switches in which the trunk lines thereof terminate, another groupof trunk lines multipled throughout the other of said sections, audalso divided into sub-groups,the trunk lines of each sub-group also terminatingin an associated group of primary switches, a

plurality of groups of inter-office trunk lines, there beinga group of said inter-office trunk lines accessible to the primary switches of each sub-group multipled'in the first section, and multiple branches of said groups of inter-oflice trunk lines accessible to said groups of primary switchesof the sub-groups multipled in the second section. 7 6. In a telephone system, a plurality of trunk lines connected to multiple jacks in a plurality of A "operators positions, a group of automatic trunking switches in which said trunk lines terminate, a second plurality of trunk lines connected to multiple jacks in a different plurality of A operators positions, a second group of automatic trunking switches in which said sec{ ond group of trunk lines terminate, a third plurality of trunk lines accessible to switches in both of said groups and terminating in a third group of autotrunking switches, a plurality of B operators positions and a plurality of cord circuits at each position, and suitable connections whereby each i switch in said third group is given access to cord circuits in all of said B positions.

7. In a telephone system, two switch boardsections each comprising a plurality of A operators positions, agroup of trunk lines multipled throughout the first section and divided into sub-groups, each sub-group having an associated group of primary switches in which the trunk lines thereof terminate, another group of trunk lines multipled throughout the other of said sections, and also divided into sub-groups, the trunk lines of each sub-group also terminat-. ing in an associated group of primary switches, a plurality of groups of inter oilicetrunk lines, there being a group of said inter-otfice trunk lines accessible to the primary switches of each sub-group multip ied in the first section, multiple branches of said groups of inter-oiiice trunk lines accessible to said groups of primary switches of the sub-groups multipled in the second section, a plurality'of B-operators cord circuits, and a plurality of secondary switches for ex tending said inter-oflice trunklines into connectionwith said cord circuits.

8.111 a telephone system, two switch lines of each sub-group also terminating in an associated group of primary switches, a plurality of groups of 1nter-oilice trunk lines, there bemg a group of said inter-oiiice